Turbine engines, such as those used as aircraft turbojets or turbofans typically include from front to rear, in the direction of fluid flow in the engine, fan, compressor, combustion and turbine sections within a housing. These sections include rotating components mounted on one or more coaxial shafts for rotation about a central axis of the engine.
The fan section draws air into the engine. It is compressed in the compressor section, and admixed with fuel in the combustion section where the mixture is ignited. Combustion gases exit the combustion section and drive one or more turbines within the turbine sections.
Typically a first stage, high pressure turbine ("HPT") blade forming part of the initial turbine section, is cooled to prevent melting by using uncombusted high pressure air, referred to as P3 air. Specifically, the P3 air is passed through a tangential on-board injector ("TOBI") nozzle. The TOBI nozzle reduces the relative total temperature of the P3 air typically by approximately 100.degree. F. (55.degree. C.). The reduced temperature P3 air is passed into a HPT disk/coverplate rotating cavity and over the HPT blade. There, the P3 air cools the HPT blade typically using showerhead cooling.
Use of high pressure P3 air, however, is thermodynamically inefficient. Moreover, a TOBI nozzle and ancillary components add weight to the engine. Similarly, showerhead cooling requires the machining of relatively complex components.
Accordingly, a more thermodynamically efficient method of cooling an HPT within a turbine engine is desirable. Moreover, an engine with reduced weight of components associated with HPT cooling is desirable.